1. Technical Field
The present disclosure relates to a liquid-crystal display device and an electronic apparatus.
2. Description of the Related Art
Liquid-crystal display devices include transmissive-type liquid-crystal display devices that displays an image by using transmission light from a backlight provided on a backside of a screen. Some of this type of liquid-crystal display devices control brightness and darkness of a pixel with 0 to 255 gradations (so-called “256 gradation” or “8 bit display”) (see Japanese Patent Application Laid-Open No. 2007-219392). In the liquid-crystal display device, when an ambient temperature is low, a response speed of a liquid crystal is decreased. Therefore, in order to improve the response speed of the liquid crystal, the liquid-crystal display device performs so-called “overdrive” in which a driving voltage for driving the liquid crystal is set to a voltage higher than a normal driving voltage.
Some liquid-crystal display devices improve the responsiveness of the liquid crystal by using a range that exhibits a fast response of the liquid crystal, when the liquid-crystal display device is used under an ambient temperature that decreases the responsiveness of the liquid crystal (see Japanese Patent Application Laid-Open No. 2010-109578). Specifically, in this type of liquid-crystal display device, a range that exhibits a fast response of the liquid crystal is set such that a black level becomes 15% of brightness of the liquid-crystal display device and a white level becomes 85% of the brightness of the liquid-crystal display device.
In this manner, when the response speed of the liquid crystal is decreased in a low ambient temperature, the liquid-crystal display device improves the response speed of the liquid crystal by performing a overdrive that applies a driving voltage higher than a target driving voltage corresponding to a target gradation in order to render a gradation of a pixel to meet a target gradation. In this case, when the gradation of each pixel of the liquid-crystal display device is controlled with 256 gradations, voltage values of the driving voltage a prepared as many as the number corresponding to 256 gradations. That is, in the liquid-crystal display device, 256 voltage values of the driving voltage are prepared, with which 0 to 255 gradation are associated. When performing the overdrive, in the liquid-crystal display device, it is required to prepare a voltage value of the driving voltage for the overdrive as well as the 256 voltage values for executing the gradation control with 256 gradations. Therefore, in the liquid-crystal display device, in order to perform the overdrive when the response speed of the liquid crystal is decreased, it is required to prepare voltage values equal to or more than the voltage values used in an 8-bit display as the voltage value of the driving voltage. In this case, as the voltage values of the driving voltage increases, a control load on the liquid-crystal display device increases.
For the foregoing reasons, there is a need for a liquid crystal display device that can suppress an increase of the control load, and an electronic apparatus including the same.